perf callchain: Switch default to 'graph,0.5,caller'

Which is the most common default found in other similar tools.
Requested-by: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Chandler Carruth <chandlerc@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://www.youtube.com/watch?v=nXaxk27zwlk
Link: http://lkml.kernel.org/n/tip-v8lq36aispvdwgxdmt9p9jd9@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-report.txt

@@ -192,7 +192,7 @@ OPTIONS
 	when available. Usually more convenient to use --branch-history
 	for this.
 
-	Default: fractal,0.5,callee,function.
+	Default: graph,0.5,caller
 
 --children::
 	Accumulate callchain of children to parent entry so that then can

tools/perf/builtin-report.c

@@ -633,7 +633,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 	bool has_br_stack = false;
 	int branch_mode = -1;
 	bool branch_call_mode = false;
-	char callchain_default_opt[] = "fractal,0.5,callee";
+	char callchain_default_opt[] = "graph,0.5,caller";
 	const char * const report_usage[] = {
 		"perf report [<options>]",
 		NULL
@@ -701,7 +701,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 		    "Only display entries with parent-match"),
 	OPT_CALLBACK_DEFAULT('g', "call-graph", &report, "output_type,min_percent[,print_limit],call_order[,branch]",
 		     "Display callchains using output_type (graph, flat, fractal, or none) , min percent threshold, optional print limit, callchain order, key (function or address), add branches. "
-		     "Default: fractal,0.5,callee,function", &report_parse_callchain_opt, callchain_default_opt),
+		     "Default: graph,0.5,caller", &report_parse_callchain_opt, callchain_default_opt),
 	OPT_BOOLEAN(0, "children", &symbol_conf.cumulate_callchain,
 		    "Accumulate callchains of children and show total overhead as well"),
 	OPT_INTEGER(0, "max-stack", &report.max_stack,

tools/perf/util/util.c

@@ -17,9 +17,9 @@
 #include "callchain.h"
 
 struct callchain_param	callchain_param = {
-	.mode	= CHAIN_GRAPH_REL,
+	.mode	= CHAIN_GRAPH_ABS,
 	.min_percent = 0.5,
-	.order  = ORDER_CALLEE,
+	.order  = ORDER_CALLER,
 	.key	= CCKEY_FUNCTION
 };